Step 6: Base, step 3

Next cut the all thread to 9" lengths and assembly like in the pic.
The reason I made it this was was so that you can adjust the belt tension and level the top roller to the bottom roller. You dont have to bolt the top on permanently just yet, you need to add the motor and and comb.
<p>When you say &quot;cheap&quot; you didn't list the actual price of all the listed items needed for this project? Now my guess is that this would be over $100 so I wouldn't call it cheap. </p>
<p>Would it be fatal to discharge it using my body? As in connecting the negative to my ankles and arcing the negative charge through my hands to the positive charge on the globe.</p>
<p>i dont think this low a current will be damngerous. but you should test it first by connecting it to your wrist so you only shock your hand at worst. starting with the ankles means it may arc through your heart, which is not good.</p>
<p>thanks for the input!</p>
<p>I should add that I want to constantly discharge the electricity while the machine is on.</p>
<p>is it possible to use plastic as the collector and then place metal on top?</p>
<p>Zachary, what is the reason for the long neck leading up to the dome. Can the length of the belt be shorten to stay 3&quot; from roller to roller? If so would widening the belt with this short distance compensate for its lack of length?Thanking you in advance.</p><p>Dave</p>
<p>Using a larger ball connected to ground will increase the size and energy of the spark quite a bit as well. A good safety device is a straight paper clip. You can touch any machine without getting shocked at all if you approach it with a pointed piece of metal.</p>
<p>Any belt material will work! i used a wide rubber band</p>
Whats ur opnion about connecting the base comb wire to the motors body.....<br>
I was making one and has a dought with the top comb that. Both the combs are on the same side or not.u sayd that the comb should be placed just before the belt touches the roller...<br>A faster reply will be appreciable
<p>How large is your metal ball?</p>
<p>He said it was a 12 Inch Steel gazing ball in one of the pictures</p>
<p>Can I use this motor http://www.ebay.in/itm/High-Torque-DC-12V-Multipurpose-DIY-Brushed-Motor-/191215763246?pt=IN_Toys_Games_School_Stuff&amp;hash=item2c8558ff2e&amp;_uhb=1 ?</p>
<p>Would foam PVC sheet work well or would that be too weak? How do you recommend I attach the PVC sheet &quot;box&quot; (with the bottom roller in it) to the base? Screws/glue/both?</p><p>Thanks</p>
<p>Hi I have built the Van de Graaff generator to the best of my ability. I have one problem. The bigger pulley near the bottom roller has a inner diameter that is slightly than the diameter of the rod used. Because of this the pulley isn't able to roll the roller which is a crucial par to this. What can i do to fix this? I cant get a different pulley as there aren't any other sizes available.</p>
Help! I'm stumped! I build a VDG following these nickademuss instructions with a few ideas from the Mark Rehorst site. I used a rubber belt (Sports Authority exercise band) and nylon rollers, one wrapped in Teflon tape. I used the IKEA bowls for the dome. It is definitely generating charge, I can even see a blue glow around the bottom roller before the belt passes the pickup comb. But around the dome I can only get about a 1/2 inch spark. However, I can get much bigger sparks against the column below the dome. I added some vanes going down the column to try to help (disposable plastic plates), and now I can get even bigger sparks (6 inches) down the column (and through the plates, it seems), but still only 1/2 inch anywhere else on the dome. Anyone have any ideas what I'm doing wrong? <br> <br>
<p>sorry for the delayed response, As mentioned in this instructable vinyl belts work best with my design.</p><p>ANY raised edges on the surface of your collector cause the voltage to bleed off into the air, it has to be a smooth dome or torid to hold the charge. First try the right belt, then get yourself a garden gazing ball like the one I used.</p><p>Also if you don't have the copper ring for the collector to sit on, you will lose allot of the charge at the base of the sphere. Hope this helps</p>
<p>Thanks for the response! I could not find the vinyl fabric to use for belts locally, so I went with the rubber belts. I don't think that's the problem, as I can draw a 30cm hot visible spark down the column, just not out perpendicular to the unit.</p><p>I have the dome on a copper ring, but it's 3/8 inch tubing, not 3/4. I could not find any 1/2 or 3/4 inch that I could bend without breaking. What did you use?</p><p>My suspicion now is that the IKEA bowls are brushed stainless, not a mirror smooth finish, and that may be bleeding off a lot of charge diffusely. I can get a blue corona discharge from a pointed rod as far as a meter away from the dome, and a car ignition wire tester (neon bulb in a wand) will illuminate steadily even further away than that. So there is a lot of charge in the air, and a rod in the area must discharge that before enough can build up to make a big arc. </p>
I found some great rollers at Walmart. They were nylon bed casters, about 2 1/4 inch wide, and fatter in the middle to keep the belt centered. I used on as is and wrapped another in Teflon tape. I drilled the rivet out of the caster and just used the roller on my own axle (it needs a 1/4 inch axle). Everything I could find about this product from other web sites says the roller is nylon, though you can't get that info from Walmart. <br> <br>Here's the Walmart product link: <br> http://www.walmart.com/ip/Soft-Touch-Bed-Caster/16782119 <br>
i am unable to find teflon roller an nylon rollers in my area now what can i use?can i wrap a bed roller in teflon tape to use it instead of teflon roller?THANKS IN ADVANCE
I just got done building mine and it works great! Thanks for the instructable.
Here's a picture
and another
GREAT JOB! looks awesome!
I have one question: How did you get close to 900kv with this small 12&quot; sphere? It is just impossible, for instance the absolute maximum theoretical voltage you could get out of a 12&quot; sphere is V = 3x106r= maximum of 450kv but in reality it would fall below 300kv.... How come you got huge sparks, you see?
Is stainless steel positive or negatively charged or neutral and would it work for the gazing ball??
does anybody know how to make a discharge wand?
Hi, thank you for a marvellous instructable! I am planning to build a machine based on these instructions. I have a question: in your instructions, there is a platform implemented at the top of the tube to mount the roller and charge comb on. But my friend and I are thinking about mounting the top roller on an axle that simply rests in cutouts in the side of the tube itself. Of course, it would protrude a little meaning that the hole in the sphere would need to be enlarged a bit - at least where the axle pokes out. But can you think of any fundamental reason why it wouldn't work? The whole thing would be within the radius covered by the copper ring that the sphere rests on. Thanks so much for your opinion!
I have a doubt, if this Van De Graff generator can produce 900,000 volts, then why can't we use it for electric supply for a house? or other purposes?
it does not make energy, it feeds of a battery or wall power, and converts that into a high ponental static electricity. <br> <br>even though the voltage is high, the current is super low. try to make a light bulb light up or a motor spin. this type of high voltage/low current will just shoot straight though any low-impedance load. (coils of wire in a motor, or a filament in a lightbulb).
Just because it's called a Van de Graaff generator doesn't mean that it's an electrical generator or &quot;energy source&quot; capable of producing a usable current like the ones in a power plant.
No we cant because eventhough its 900,00 volts, the current( I ) is low.
Study basic electronic theory.
and i forgot to say, a house needs like 50 amps so 0.2209 amps would power a 25 watt light bulb, it probably couldnt even power your laptop. And also van der graafs need to charge up to 900000v, its not constant. so powering a house would simply be impractical.
the amperage is also far too low: 900,000 volts at 27 micro amps will produce 110v at 220.9 milli amps (0.2209 amps) when a house requires far more amps then that. and not to mention the losses when converting 900000v to 110v
This generates static electricity, and voltage like this isn't that useful. It will jump through insulation on wires, and the amperage of this is also extremely weak.
I built one similar to this in '92. I worked for a company that built very high power coax equipment for tv + radio broadcasting. The rule-of-thumb for electrical arc in dry air is 70000 volts/in. An engineer I worked with said &quot;I'd be careful about spending much time with that&quot;, he did not explain why... later I read that electrical discharges (arcs) over 300000 volts generate x-rays (at 70k volts/in thats about a 4.3&quot; arc). I used a 14&quot; diameter globe and had visible arcs about 12&quot; and non-visible ones snap at my knee when approaching at about 30&quot;. If you have one of these put a cheerio on top... it will build a charge, jump upright like a tire (from a lying flat position) and then the repelling charges will make it fly away. My kids found that white styrofoam particles would travel about 10ft through the air and cling to the sphere, then if you discharged the sphere (make it arc) all the particles would drop off for a moment and then jump back up when the charge returns!
For extreme Van de Graaff Generators check out www.physicsplayground.com <br> <br>
I am a little confused how did you calculate what your voltage would be for this generator
I'm younger then 16, so I don't exactally have a lot of money, so I was wondering, how much would all of this cost. And also, the links to buy the rollers do not work anymore, please fix them.
NA I like broken links.... <br> <br>they are no longer available from Granger, try cole parmer or use bed frame rollers available from home depot.... <br> <br>Cost depends on how much used stuff you can scrounge, mine was around 150.00 or a little less if you go to a good thrift store and buy a 5.00 sewing machine. <br> <br>Its also scalable, build a smaller one with smaller dimensions, it will be cheaper.
Your instructions are nicely done. The adjustment of the brushes could be made if you use a spacer like paper of various thickness to make positioning easier and more parallel. I haven't started yet but I assume the belt will have a tendency to centrifugally move towards the brushes if they are above the tangent point off the rollers? You say to move them just above where the belt is starting to loose contact with the roller. Are you saying that is very important or can the brushes be at the tangent of belt and roll? If so, then the likelihood of scraping is reduced.
If you use the right kind of belt it doesn't flair out very much. <br> <br>You will find out that running the belt really fast doesn't help much because of leakage at the sphere to the air. <br> <br>
I have found that you can make rings or coils very nicely by first filling the tube/pipe with sand. You must make sure there are no cavities otherwise the walls will collapse in very small diameter rings or coils. This has been an extremely effective way to make cooling coils for the technology I work in. Also make sure the sand is contained to prevent it falling out. Moonshine anyone?
I think it would be a good idea to swap the rollers over as the negative charge on the dome i have heard can attract radioactive residues but any way great design you came up with
We ended up just using a motor from an old singer sewing machine that does not have a ground. Could we use one of the metal threaded rods for a ground for the bottom Comb?
Yes, use the ground on a three prong plug and you should be fine
So, I was hoping to build one of these for my science fair at school, and I was just wondering if there are certain safety problems. For example, if you were to touch this would it really hurt or kill you or wipe out your computer or something? This is very cool and I don't know too much about them so any help would be super appreciated.
Read the instructable, it describes issues I have had...<br><br>It wont kill you, (unless you have a pacemaker or other heart problems)<br>It does sting a bit when it shocks you....<br><br>I have stopped a watch with it, killed a cell phone, knocked a wired network out....so electronics and this VDG dont mix!

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Bio: Electronics engineer with allot of mechanical design expertise
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